const highlight_tag = new RegExp('</?span.*?>', 'gi');

const s = '南极人<span class=H>男</span>士内裤<span class=H>男</span>纯棉平角裤大码青年性感四角裤潮<span class=H>男</span>生夏季短裤头';

s_cleaned = s.replace(highlight_tag, '');

console.log(s_cleaned);